It seems there's no modern emulator for the Mac that runs under El Capitan, but it would be nice to see a Windows emulator support high resolution displays, such that I could use Wine on my 5k iMac to display the 28S (and other calcs) in actual size, photorealistic glory!

Lastly, the MIDI music mentioned by the previous poster doesn't play on the iPad.

(07-02-2016 07:45 AM)JDW Wrote: FTP links are not supposed to start with http://, therefore you need to check your original source.

This is a known problem with the Forum software. You can't create a true ftp link, it gets munged into a non-working http: link. In this case, you can just show what the ftp link should be, without inserting a true link, so folks can copy/paste. Most likely, the correct link works, but I have not checked.

Just remember, the HP28 is a closed system with less public information and no public tools to write "System Objects". The offical way to call SysRPL-Objects is SYSEVAL from UserRPL. But the SYSEVAL numbers wasn't public at all, so some very enthusiastic people try to discover these secrects at end of the 80'ies. The list at http://www.hpcalc.org/details.php?id=408 is an example of such a work.

For the successor HP48SX soon after Joe Horn began his Horn Disk series. Around 1992 Joe published Horn Disk 4 which contain the HP-TOOLS, a collection of SysRPL-Compiler, Assembler, Linker, entry point list and documentation around SysRPL and Assembler programming especially for the HP48S(X).

The entry point list is a collection of the entry point names and the corresponding SYSEVAL address for use with the HP-TOOLS Assembler/Linker package. The delivered documentation tell for some entry point names the working and the input and output variable types.

There are no official entry point lists for the HP28C 1BB, 1CC or for the HP28S 2BB. Decades ago JFG began to write a 700 items large entry point list for the HP28S using the entry point names of the HP48SX. With the tools inside Emu42 I was able to increese the list to over 2500 items over the years.

So why we know that =SUB$ has address #041CF in the HP28 2BB ROM?

That's easy, we compared the ROM disassembly of the HP28S with the one from the HP48SX. If the dissassembly is equal we found the named entry point in the HP28 ROM. There're still many gaps in the HP28 ROM entry point lists, these are unnamed entry points or there's no source code equivalent in the HP48. Especially graphic output routines are affected by this.

So back to the entire question, with the entry point list at http://hp.giesselink.com/Emu42/suprom28.zip and the HP-TOOLS you can write SysRPL and assembly programs in the same style like writing such programs for the HP48. How you get such programs inside the HP28 is a different question.